What's the last date I can post this to  to arrive in time for Christmas? http://www.inatownthissize.com/eassy-writting/ essay college  Coal-fired power plants are the single-largest source of U.S. electricity, providing 37% of the total last year. They also emit a disproportionately large share of greenhouse gases 但ﾂ�ﾂ� far more that natural gas counterparts. While they provided 18% of all energy consumed nationwide in 2012, they accounted for 31% of energy-related carbon-dioxide emissions, according to the U.S. Energy Information Administration.